106 TRANSACTIONS, NATURAL HISTORY SOCIETY OP GLASGOW. 



the Sigillarue were an arborescent form of Isoi'fes.^ This opinion 

 is fully borne out by subsequent discovery, for a small specimen 

 of Sigillariostrohus ciliatus, Kidston, collected at WooUey Colliery, 

 Darton, near Barnsley, from the Barnsley thick coal," by Mr. W. 

 Hemingway (No. 2144), shows the sporangia (in this case macro- 



B 



sporangia) to be included within the 

 inflated base of the sporophyll, which 

 clearly unites the Sigillai-ia with the 

 Isoetes, as their nearest living ally.' 

 The sporangia are here seen to be 

 placed in the hollow basal portion 

 of the sporophyll, whose surround- 

 ing walls unite again in front of the 

 sporanginno to form the upward 

 rising sporophyll blade. 



Zeiller has suggested that perhaps 

 some Sigillarian cones bore macro- 

 spores, and others the microspores, 

 because in the case of his Sigillari- 

 ostrohus nohilis * no spores were 

 observable between the bracts, and 

 had macrospores been present they 

 would almost certainly have been 

 seen, therefore, he suggests, that 

 this cone may have borne micro- 

 spores. But the absence of spores 

 in this case may be equally well 

 explained by supposing that the cone had reached maturity, and 

 the spores shed before fossilization took place 



Though it is not, therefore, yet satisfactorily determined 

 whether the cones of Sigillaria were heierosporous or isosporous, 

 I incline to the former view, and the evidence on which I have 

 formed this opinion is derived from a specimen collected by Mr. 



x4 



Fig. IS. — Sigilliariostrobus cili- 

 atus, Kidston. A, two spor- 

 angia containing macrospores 

 ( X 4). B, restoration of spor- 

 angium — a, axis ; b, wall of 

 sporangium. 



^l. c. Heft. I., p. 25. 



- Middle Coal Measures. 



" Kidston, " On the Fossil Flora of the Yorkshire Coal Field," 2nd paper, 

 Tram. Roy. Soc. Edin., Vol. XXXIX., Part i., p. 54, PI. II., figs. Sand 3a. 



* Zeiller, Ann. d. Science Xat., G- Ser. Bot., Vol. XIX., p. 267, PI. XII., 

 figs. 1, 2, and 2a, 



